Treatment methods for lacrimal duct obstruction resulting in epiphora include: (i) probing by a lacrimal duct bougie; (ii) placement of a lacrimal duct tube; (iii) dacryocystorhinostomy (DCR); (iv) lacrimal canaliculization; (v) nasolacrimal duct plastic surgery; (vi) lacrimal caruncle moving surgery, and the like.
The probing by a lacrimal duct bougie in (i) is intended to insert a narrow tube called bougie into a lacrimal duct to open an obstructed site and reconstruct a flow path for a lacrimal fluid. This method is conducted as a first treatment in many cases due to its ease of execution and minimal invasiveness. The treatments (iii) dacryocystorhinostomy (DCR), (iv) lacrimal canaliculization, (v) nasolacrimal duct plastic surgery, and (vi) lacrimal caruncle moving surgery are highly effective but relatively invasive because of the need for creation of incisions in a patient's face or drilling holes in bones, and thus are conducted as a last resort.
Lacrimal duct tube for use in the treatment method (ii) is, after the probing by a lacrimal duct bougie (i), placed for maintaining of a flow path and reconstruction of tissues. The placement of a lacrimal duct tube (ii) is easy, less invasive, and highly effective as compared to the foregoing treatment methods (iii) to (vi), and thus is widely performed all over the world. Among such instruments, there is widely available a lacrimal duct tube in which a central part of the tube is formed by a narrow and soft tube or rod and both sides of the tube are formed by hard and thick tubes, as disclosed in Patent Document 1 (for example, refer to FIG. 1).
The lacrimal duct tube includes a tube and a pair of bougies that is inserted from incisions at both sides of the tube, and the bougies are operated to guide the tube into a lacrimal duct and place the tube there. As shown in FIG. 2 of Patent Document 1, a lacrimal duct is formed by lacrimal puncta (21 and 22), lacrimal canaliculi (23 and 24), a lacrimal sac (26), a nasolacrimal duct (27), and others. The lacrimal duct tube is inserted into the lacrimal duct.
However, to insert the lacrimal duct tube, it is necessary to fumble for intra-lacrimal duct operations. The bougies are blindly operated and thus may break through the tube or make a hole at a site other than in the normal lacrimal duct (creating a temporary path), which results in poor therapeutic outcomes. Accordingly, to solve the foregoing problem, the inventor of the present invention has suggested in the past a lacrimal duct intubation instrument in which openings are formed at the tips of a lacrimal duct tube, reinforcement bodies are arranged and held in the vicinities of the openings, and the positions of the reinforcement bodies are adjusted within predetermined distances from the openings (refer to Patent Document 1).
In the recent year's field of lacrimal duct obstruction treatment, surgeries have been newly conducted based on a sheath guided endoscopic probing. At these surgeries, a sheath as an outer casing made of Teflon (registered trademark) or polyurethane covering a lacrimal endoscope was advanced ahead of the lacrimal endoscope in the lacrimal duct to observe from behind that the tip of the sheath opens the obstructed site in the lacrimal duct. In addition, exact tube insertion is allowed by using the sheath as a guide for tube insertion. This technique will be specifically described below. First, the sheath attached to the lacrimal endoscope is inserted into an obstructed site in the lacrimal duct and passed through the obstructed site, and then the lacrimal endoscope is removed. Next, a lacrimal duct tube is connected to the sheath, and the sheath is pulled from the side opposite to the connection side of the lacrimal duct tube to let the lacrimal duct tube pass through the lacrimal duct. Then, the sheath is removed to place the lacrimal duct tube in the lacrimal duct.
However, according to the foregoing surgery, there is the need for a step of connecting the sheath inserted into the patient's lacrimal duct to the lacrimal duct tube. In addition, occurrence of the disconnection may result in an unsuccessful surgery. Thus, there is room for improvement in the method to secure manipulation of the instruments and reduce complexity of the operation.
Meanwhile, instead of using the sheath, a lacrimal endoscope may be inserted into a lacrimal duct tube. For example, as lacrimal duct tubes usable with a lacrimal endoscope therein, there are known: 1) a lacrimal duct intubation instrument as described in Patent Document 1 that has openings at the terminal ends of a lacrimal duct tube and reinforcement bodies arranged and held in the vicinities of the openings, the positions of the reinforcement bodies being adjusted to be at predetermined distances from the openings; and 2) a lacrimal duct treatment tool including a lacrimal duct placement main body that has an outer diameter allowing insertion into the lacrimal duct and is formed from flexible material and sheath parts composed of flexible cylindrical bodies that are provided at the lower ends of the lacrimal duct placement main body and are formed from harder material than that for the lacrimal duct placement main body (refer to Patent Document 2).
However, the lacrimal duct intubation instrument described in Patent Document 1 has a complicated lacrimal duct tube structure, and the reinforcement bodies cannot be significantly smaller in diameter, and the terminal ends of the tube are difficult to harden and thus tend to be slightly weak in pressing force (pushability). In addition, when performing operations with the lacrimal duct tube, it is necessary to carefully operate the endoscope inserted into the tube because friction between the lacrimal duct tube and the endoscope becomes large depending on the material for the lacrimal duct tube. Further, the lacrimal duct intubation instrument described in Patent Document 1 (refer to FIGS. 1 and 3(a) in particular) has insertion portions at the cylindrical parts for insertion of a bougie or a lacrimal endoscope. The insertion portions are slits or tiny holes that are small enough for insertion of a bougie or a lacrimal endoscope. In the case where the insertion portions have such a structure, when, while one cylindrical part is inserted from one lacrimal punctum into the lacrimal duct and held at a predetermined position, an attempt is made to insert the other cylindrical part from the other lacrimal punctum into the lacrimal duct, it may be difficult to insert the other cylindrical part into the other lacrimal punctum. This is because the small insertion portions are provided near the centers of the integral tubes, the bougie or the lacrimal endoscope is of low flexibility, and the like.
The lacrimal duct treatment tool described in Patent Document 2 has also small through holes for insertion of a lacrimal endoscope camera in the sheath parts near the lacrimal duct placement main body. The lacrimal duct treatment tool is entirely long, and even when one sheath part is inserted from one lacrimal punctum into the lacrimal duct and held at its position, the other sheath part can be inserted from the other lacrimal punctum into the lacrimal duct. However, in the case of using the lacrimal duct treatment tool, it is necessary to separate the lacrimal duct treatment tool main body and the sheath parts after placement of the tool in the lacrimal duct, which results in complexity in performing surgeries.
In the conventional lacrimal duct tube as described in Patent Document 1 or 2, the small openings (corresponding to the insertion portions described in Patent Document 1 or the through holes described in Patent Document 2) for insertion of bar-like operative instruments such as lacrimal endoscopes are provided at the side walls of the cylindrical parts or the sheath parts, and a bar-like operative instrument is placed on the outside of the lacrimal duct tube on the central member side (the central part described in Patent Document 1 or the component with reference sign 3 illustrated in FIG. 1 of Patent Document 2). In this case, as illustrated in FIG. 11(a), for example, when a conventional lacrimal duct tube 101 is inserted into a lacrimal duct such as an upper lacrimal canaliculus 3 from an upper lacrimal punctum 1, the total width of the lacrimal duct tube 101 and a bar-like operative instrument 9b is equal to a width H1 of the lacrimal duct tube 101 at the side into which the bar-like operative instrument 9b is inserted (refer to FIG. 11(b)). However, at the side of the lacrimal duct tube 101 nearer to a central member 103 across an opening 102, the bar-like operative instrument 9b and the slightly deformed lacrimal duct tube 101 overlap each other, and the total width of the two is a width H2 (refer to FIG. 11(c)), which is larger than the width H1. Accordingly, it is difficult to insert the lacrimal duct tube 101 into the lacrimal duct beyond the opening 102, which becomes a larger burden on the patient. In addition, at the side of the lacrimal duct tube 101 nearer to the central member 103 across the opening 102, the bar-like operative instrument 9b comes into contact with edge 104 of the opening 102 in the lacrimal duct tube 101 at the central member 103 side, which interferes with longitudinal movement of the bar-like operative instrument 9b, thereby making the operation hard to perform.